The present invention relates to the field of implantable electrodes, and more particularly to a multicontact band type electrode array. In a preferred embodiment, such multicontact band type electrode array is used with an implantable stimulator to provide electrical stimulation to body tissue, for example, to brain tissue for brain stimulation, to selected nerves for neural stimulation, or to the spinal cord for spinal cord stimulation (usually done to control or manage pain). Additionally, the present invention further provides a simple and reliable method of constructing a multicontact band type electrode array.
Spinal cord and other stimulation systems are known in the art. For example, U.S. Pat. No. 3,724,467, teaches an electrode implant for the neuro-stimulation of the spinal cord. A relatively thin flexible strip of physiologically inert plastic is provided as a carrier on which a plurality of electrodes is formed. The electrodes are connected by leads to an RF receiver, which is also implanted, and which is controlled by an external controller.
In U.S. Pat. No. 5,458,629, a method of making an implantable ring electrode is taught. The method disclosed in the '629 patent describes an electrode array with a first lumen containing electrical conductors and a second lumen adapted to receive a stylet. In contrast, the multicontact electrode array of the present invention requires only one lumen, and thus the fabricating steps described in the '629 patent differ from those taught by the present invention. Moreover, the '629 patent teaches that notches must be formed in the lead body to position the electrode members, whereas the present invention does not require such notches.
Other implantable electrodes, electrode arrays, and features of implantable electrodes are taught, e.g., in U.S. Pat. No. 5,097,843 (a porous electrode); U.S. Pat. No. 5,267,564 (a built-in sensor); U.S. Pat. No. 5,423,763 (a suture sleeve for anchoring the lead body); U.S. Pat. No. 5,447,533 (a combination electrode and drug delivery system); U.S. Pat. No. 5,466,253 (a crush resistant multiconductor lead body); U.S. Pat. No. 4,819,647 (a spirally-shaped electrode array); U.S. Pat. No. 5,833,714 (electrodes made from tantalum); U.S. Pat. No. 6,112,124 (electrodes separated by dielectric partitions or fins); and U.S. Pat. No. 6,070,105 (modiolus-hugging electrodes for insertion into cochlea). The materials from which an implantable electrode array is made, including many of the manufacturing techniques, disclosed in these patents may also be used with the present invention. For that reason, the patents listed in this paragraph are incorporated herein by reference.
However, despite the various types of implantable electrode arrays known in the art, significant improvements are still possible and desirable, particularly relating to reducing costs and providing a more reliable construction based on new manufacturing technology.
Most designs of electrodes and connectors, for example, are based on the principle of molding a contact or array of contacts, usually made from biocompatible metal, into a polymer carrier, such as silicone or polyurethane rubber. The electrode contacts are usually required to be located in a controlled position in reference to the surface of the carrier, with specified surface areas to be fully exposed to the stimulated or interconnection area. Disadvantageously, making such electrodes or connectors becomes extremely difficult, especially when the contacts are very small and/or a large number of contacts are required. One of the main problems encountered in the fabrication of such electrodes or connectors is to find a reliable method of holding the system of contacts in the desired and stable position during the process of welding the connecting wires and during the process of molding the polymer carrier. A further problem relates to maintaining a controlled surface of the contacts that are to remain exposed, i.e., to ensure that the contacts are not covered by the polymer when the carrier is molded.
It is thus seen that there is a continual need for improved, more reliable, implantable multicontact electrode arrays that are simpler to make and less costly to make.